1. Technical Field
The invention relates to a clip unit and a ligation device using the same.
2. Related Art
In general, a ligation device includes a clip unit located at a front end of an elongated flexible sheath extending from a handle manipulation unit. The clip unit is driven by reciprocating a manipulation wire, which is inserted through the sheath, in the axial direction of the sheath or by rotating the manipulation wire around the axis of the sheath at the handle manipulation unit. An endoscope operator may introduce the clip unit into a body cavity by inserting the sheath of the ligation device into a treatment instrument insertion channel formed in an insertion part of the endoscope. This type of ligation device is described, for example in Patent Document 1 (JP-B-4116049) and Patent Document 2 (JP-B-4472719).
A clip unit 301 is embedded in a sheath 303 as illustrated in FIG. 47A when introduced into a body cavity, and the clip unit 301 extends to the outside and revealed from the front end of the sheath 303 as illustrated in FIG. 47B when arriving at a target affected part. The clip unit 301 is provided with flap parts 305, 305 elastically biased diametrically outward, so that when the flap parts 305, 305, which have been closed within the sheath, protrude from the sheath 303, the flap parts 305, 305 are expanded diametrically outward. Once the flap parts 305, 305 are expanded, when the clip unit 301 is pulled into the sheath 303 side, the rear end of the flap parts abuts against the front end of the sheath, thereby being stopped. As a result, the clip unit 301 is positioned in relation to the sheath 303, in which the position is set as a treatment starting position.